Osoriellus rufescens, Irmler, 2014

Irmler, Ulrich, 2014, The Neotropical species of the genus Osoriellus FAGEL, 1959 (Coleoptera: Staphylinidae: Osoriinae), Beiträge Zur Entomologie = Contributions to Entomology 64 (2), pp. 231-354 : 306-307

Osoriellus rufescens n. sp.

( Figs 122 A-C, 126A)

Type material: Holotype, male: Peru: Dept. Loreto, Campamento San Jacinto (75°51.77'W, 2°18.75'S), 175-215 m elevation, rainforest, collected by Berlese method, 6.7.1993, leg. R. Leschen ( KNHM).

Diagnosis: Among the species with digitate protibia and rectangular shoulders, the species is characterised by the presence of a pronotal setiferous punctation and the light reddish colouration. In this respect it resembles O. loreti . But it differs from O. loreti by the absence or weaker pronotal microsculpture. Furthermore, the apical lobe of the aedeagus of O. rufescence has an obtuse apex and the aedeagus is obtusely angulate, whereas the apex in O. loreti is acute and the aedeagus nearly rectangularly angulate.

Description: Length: 4.3 mm. Colouration: Light reddish brown; head and posterior margin of elytra slightly darker.

Head: 0.50 mm long, 0.87 mm wide; eyes slightly prominent; nearly 1.5 times as long as temples; sides of fore-head convergent to anterior angles in deep sinuate curve; close to anterior angles parallel; anterior edge of clypeus even; setiferous punctation sparse and moderately deep; wide midline and area at base of antennae impuncate; on vertex, interstices between punctures as wide as diameter of punctures; on supraocular area slightly denser; length of yellow setae approximately as long as interstices between punctures; isodiametric microsculpture weak; surface with iridescent shine.

Antennae nearly as long as head and half of pronotum combined; second antennomere oval; slightly longer than conical third antennomere; following antennomeres increasing in width, but all approximately quadrate.

Pronotum: 0.87 mm long, 1.02 mm wide; widest close to anterior angles; anterior angles rectangular; in anterior half, sides slightly convergent, to posterior angles; in posterior half; sides emarginate; close to posterior angles parallel; posterior angles widely rounded; posterior edge nearly as wide as anterior edge; lateral margin fine in anterior half; widened in posterior half; in dorsal aspect, covered close to anterior angles; setiferous punctation deep and moderately dense; wide midline impunctate; on average, interstices 1.5 times as wide as diameter of punctures; at midline slightly denser than laterad; yellow setae approximately as long as interstices between punctures; without microsculpture, but with dense micro-punctation; surface moderately shiny.

Elytra: 1.07 mm long, 1.02 mm wide, shoulders distinctly rectangular; even slightly produced laterad; sides parallel; setiferous punctation weaker than on pronotum and hardly visible in deep coriaceous ground-sculpture.

Abdomen with setiferous punctation dense and weak; yellow setae much longer than interstices between punctures; wide midline on tergites impunctate; without microsculpture, but with iridescent shine.

Protibia: 0.46 mm long, 0.11 mm wide; outer edge with 8 spines; apical spines inserted on moderately long digits; WLR: 0.70; in posterior aspect, comb at inner emargination visible throughout its total length; on posterior face long yellow setae in transverse rows.

Aedeagus obtusely angulate; apical lobe short and evenly curved to obtuse apex; inner edge with sparse row of sensillae.

Etymology: The specific name rufescens derived from the same Latin word meaning reddish and refers to the light reddish brown colouration.

Figures

Fig. 119-122: Remaining-species-group: Osoriellus weberi (119), O. infuscatus (120), O. rectangulus (121), O. rufescens (122); antenna (A), protibia (B), aedeagus in ventral and lateral aspects (C); scale bar: 0.1 mm.